1. M EASUREMENT AND T OOLS AND T ECHNIQUES OF THE B IOLOGIST

2. H OW D O S CIENTISTS M EASURE T HINGS ? Measurements in most scientific research are always expressed in units of the Metric System The units of the Metric System are based on units of ten This is very different from the Standard System used in the United States!

3. B ASIC UNITS OF MEASUREMENTS Guess that unit! Basic unit of length = Basic unit of mass/weight = Basic unit of volume = Basic unit of temperature =

4. M ETRIC S YSTEM S UMMARY Unit TypeMetric System Standard System Equivalent Equipment Used LengthMeterYard, MileMeter Stick Mass/WeightGramPoundBalance Scale VolumeLiterOunce, Cup, Pint, Quart, Gallon Graduated Cylinder TemperatureCelsiusFahrenheitThermometer

5. M ICROSCOPIC M EASUREMENTS In this class we will be using a compound light microscope to view tiny specimens and cells The unit of measurement used to measure tiny objects is the micrometer (µm) One meter = 100 millimeters (mm) 1 millimeter = 1000 micrometers!

6. C ONVERTING B ETWEEN M ILLIMETERS AND MICROMETERS 1 millimeter = 1000 micrometers To convert millimeters to micrometers, move the decimal point 3 places to the right Example: 5.0 mm = ____ um.005

7. Y OU T RY IT ! 1. 3.2 mm = ____ µm 2. 0.4 mm = ____ µm 3. 0.01 mm = _____ µm 4. 500 µm = _____ mm 5. 45 µm = _____ mm

8. T OOLS OF THE B IOLOGIST New scientific instruments and techniques have allowed biologists to increase their understanding of cell structure and function The most important tool has been the microscope, which from its invention in the 1500s has completely changed the study of biology History of the Microscope

9. T HE C OMPOUND L IGHT M ICROSCOPE Uses two lenses, the ocular and the objective lenses One lens enlarges the specimen and the second magnifies it even more Specimens must be wet mounted This is the microscope we will be using in the lab

10. P ARTS OF THE C OMPOUND L IGHT M ICROSCOPE

11. 1. Body Tube - hold eyepiece lens at the top and objective lenses at the bottom, hold mirrors inside 2. Nosepiece - rotating piece that hold the objective lenses 3. Objective Lens - lens closest to the specimen, scanning lens magnifies 4x 4. Low Power Objective Lens - magnifies 10x 5. High Power Objective Lens - magnifies 40x

12. P ARTS OF THE C OMPOUND L IGHT M ICROSCOPE 6. Stage Clips - holds glass slide in place 7. Diaphragm - controls the amount of light that reaches the specimen 8. Light Source - reflects and focuses light on the specimen 9. Ocular Lens (Eyepiece) - is used to “look through” and is closest to the eye. It usually magnifies 10x 10. Arm - holds the body tube and the base

13. P ARTS OF THE C OMPOUND L IGHT M ICROSCOPE 11. Stage - platform that holds the specimen to be examined 12. Coarse Adjustment Knob - large knob used for focusing the specimen with the low power objective lens 13. Fine Adjustment Knob - small knob used for some focusing with low power objectives and for all focusing with the high power objective 14. Base - supports the microscope

15. M AGNIFICATION To determine the total magnification of the microscope, multiply the magnification of the ocular by the magnification of the objective lens Example: Ocular = 10x Objective = 40x Total Magnification = 10 X 40 = 400

16. R ESOLUTION Resolution is the ability of the microscope to show two points that are close together, as separate images Basically, it’s how sharp of an image the microscope produces

17. V IEWING O BJECTS U NDER THE M ICROSCOPE 1. Position the specimen under the objective lens 2. Make sure the diaphragm is at its widest (allows the most light through) 3. Use the scanning lens to make sure the specimen is centered and the coarse adjustment knob to focus the image 4. Switch to low power and focus the image using the coarse adjustment first, then the fine adjustment as needed 5. Switch to high power and sharpen the image using the FINE ADJUSTMENT KNOB ONLY

18. F IELD OF V IEW The field of view is what you see when you look through the ocular As magnification increases, the size of the image increases and the field of view decreases As the power of the objective increases, the brightness of the image decreases

19. F IELD OF V IEW

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21. H OW D OES A N I MAGE L OOK U NDER THE M ICROSCOPE ? Because the body tube is filled with mirrors, the image is always viewed upside down and backwards Moving the slide to the right causes the image to move to the left (and vice versa) Moving the slide up causes the image to move down (and vice versa) e e

22. E LECTRON M ICROSCOPE Uses a beam of electrons to produce an image The electrons bounce off the surface of the specimen to create an image It can magnify objects up to 10,000,000X Used to study small structures of cells Since the microscope cannot work if the specimen is moving, the specimen must be dead

26. D ISSECTION M ICROSCOPE Also called a stereoscope or a binocular microscope Has an ocular and objective lens for each eye Gives a 3D view of the image Used during dissections and to study external structures of small plants and animals